1. Field of the Invention
The present invention relates to an additive color light source for professional photographic printing and more particularly to a lamphouse having a closed loop light intensity feedback control system for regulating the light sources within the lamphouse.
2. Description of the Prior Art
Modern photographic color printing requires a lamphouse which supplies red, green and blue light. Typically, a color printer controller computer or color negative analyzer is used to select the desired amount of red, green and blue light for a particular exposure. The additive lamphouse converts the color computer information into controlled intensity values for each of the colors. Total photographic exposure time and color balance in the final print requires accurate control over the intensity of each of the light sources.
U.S. Pat. No. 4,565,441 to Evans describes a light source for a photographic color printer which utilizes feedback control to regulate the intensity of the lamps. In this prior art device, light is withdrawn from the lamphouse mixing chamber and the color balance is monitored by circuitry which is used to generate error signals. The error signals may be combined with control signals from a conventional color printing processor computer, and used to control the current delivered to the lamps.
U.S. Pat. No. 4,371,259, to Howitt, teaches a digital color printer system in which a microprocessor is used to compute and store various color value and exposure data information for use with an additive color printer.